When I purchased my condominium 12 years ago, the seller had an old dog that had had several “accidents” on the carpet over the years.

To my surprise, the seller no longer even noticed the urine odor, but just about everyone else did.

Because the carpet was one of the things I liked most about the unit, I hired the best carpet cleaner I could find in the Chicago area. Once known as “Oprah’s iStock/Dixiecarpet cleaner,” he apparently had done some work for her and his calendar was typically booked weeks in advance.

I explained the odor problem to him and, fortunately, because I was to move in fairly soon, I did not have a lengthy wait.

The carpet cleaner first vacuumed the carpet and then applied a cleaning agent designed to remove pet odors. This product also had a fragrance to help mask the odors.

This was followed by running a floor machine, similar to those used in bonnet cleaning, over the carpet. He then used a portable extractor to “flush the carpet,” as he referred to it, and extracted the moisture and cleaning solution from the carpet.

His final steps included grooming the carpet and placing air movers to speed dry the carpet.

As you can imagine, the carpet looked great and not only was the odor gone, but the pleasant fragrance could be detected even in the building’s hallway. Everything was dandy for about four days.

Odiferous issues

After those four days, the odor returned. It returned with a vengeance! Eventually, the carpet had to be replaced.

So what went wrong?

An even better question might be, “What can carpet cleaning technicians learn from this incident?”

The key lessons are the following:

  • Although there are many fine products available for pet odor removal, there are no “magic potions” or cleaning systems that will work on every carpet in all pet odor situations.
  • Ask the customer questions. If the pet “accident” problem has been going on for a long period of time, it increases the likelihood that the pad and subfloor are saturated with urine and cleaning the surface of the carpet alone will prove futile.
  • Never promise or guarantee that the pet odor will be eradicated. According to Ruth Travis, a recognized carpet cleaning expert, if you believe the situation can be improved, it is better to say, “We will work hard to reduce the odor to the point that it is no longer a problem.” However, even this may be promising too much.
  • Become trained in deodorizing techniques before attempting pet odor removal.
  • Educate your customers about the practical limitations of odor removal.

As to what possibly went wrong in the scenario outlined at the beginning of this article, there is no one answer. So let’s go through some of the key steps in removing urine and pet odors from carpet. But remember, some of these steps may not be applicable to area rugs or all types of carpet fibers.

Chemical selection

First, determine if the carpet can be saved or if it would be better to replace the affected areas, and clean and deodorize the subfloor. If the decision is to save the carpet, the first step, and one of the most important, is to select the proper chemical to use.

According to Travis, this will be based on the fiber and construction of the carpet. “Products that are commonly used and are appropriate for synthetic fibers can be disastrous on wool or silk or other natural fibers,” says Travis. This is likely true for fibers such as cotton, sisal and others.

If the carpet is wool, the types of chemicals to avoid include cationic (quaternary ammonium chloride) disinfectants; enzyme deodorizers containing protease or having a high pH, because they can permanently damage wool; alcohol-based disinfectants; and oxidizing deodorizers that contain hydrogen peroxide or sodium perborate, because these can damage natural fibers.

Travis cautions against using oxidizers on nylon as well, as most nylon carpet is acid dyed and subject to color loss. 

“It’s important to choose an appropriate deodorizer for wool or silk, as well as nylon carpet fibers,” Travis said. “This would be a low-pH or acid-based product combined with detergents to dissolve, emulsify and suspend urine contamination.”

On the other hand, cleaners don’t have as many chemistry concerns when dealing with odor and stain challenges on olefin or polyester fibers, since high pH, enzymes and most oxidizers aren’t an issue.

As most technicians know, they should follow manufacturer recommendations for their cleaning and deodorizing solutions. Some products should not be mixed together as a negative reaction can occur.


With the deodorizer properly mixed, the product should first be tested on the carpet for colorfastness. A properly mixed and diluted application should then be applied to the individual problem areas following the manufacturer’s instructions. Allow sufficient contact time for the product to penetrate, dissolve and neutralize the source of the odor.

“The carpet or rug should [then] be slowly and carefully cleaned overall using hot-water extraction,” according to Travis. “Wicking residues may require a second or even a third rinsing.” 

Some carpet care experts question the use of hot water when removing urine odors because urine is a protein and it is often best to use cold water when cleaning carpet that have been stained with blood, eggs or other food, all of which are proteins. Further, when bacteria and enzyme product combinations are used to break down the urine, temperatures less than 115 degrees Fahrenheit are advised as higher temperatures can damage and/or slow down the activity of the enzymes.

However, if enzymes are not part of the odor elimination strategy, Travis and other carpet cleaning experts usually recommend the use of machines that generate heat (hot-water extraction systems) because heat improves cleaning effectiveness.

According to Bob Abrams, the carpet care product manager for Nilfisk-Advance, the manufacturer of the U.S. Products brand of professional carpet extractors, “When it comes to pet odor removal, you want to use the best tools, chemicals and equipment possible, and that typically includes machines that heat the cleaning water or solution.”

Abrams also advises:

  • Do not oversaturate carpet with chemical solution.
  • Use air movers to dry carpet, if possible.
  • Don’t rely on masking deodorizers only. Not only do they often fail to fix the problem permanently, some people find the fragrance of these products unpleasant, and as we will discuss in greater detail later, “Fragrances or masking agents typically deal with the psychology of odor more than the actual elimination of odor,” explains Abrams.

The next step is very simple: Wait. If all goes well, or reasonably well, the pet odor will be reduced enough so that it no longer is a problem. If the odor does return and a “call back” is requested, make sure the source — the dog, cat, or “other” — has not returned to the scene and re-contaminated the carpet.

In such cases, the technician may need to play carpet inspector, using a black light, ultraviolet high-intensity light or a moisture detector that alerts the user when moisture is detected to look for possible new accidents.

Psychological odors

If you remember, when I purchased my condominium the seller mentioned she never noticed any urine odor. Hard as it was to believe, it may very likely have been true.

Conversely, customers who have called in a technician or cleaning professional specifically to remove a pet odor may still believe the odor exists, even though no one else does.

What’s happening, says Doug Heiferman, a textile maintenance and restoration industry trainer and consultant, is this: “Simply put, 90 percent of odor is psychological in nature.”

And while he says this is most evident in fire and restoration situations, it can apply to other odor problems, including pet odor removal.

Other experts suggest that because many odor problems are psychological or emotional issues, even if the odor has been effectively eradicated or reduced significantly, customers may say they can still smell it at a level as bad or almost as bad as before the cleaning.

In a fire restoration situation, Heiferman says we must remember that the customer has just gone through a “traumatizing” experience, and may not necessarily be a “rational human being.”

For some people, according to Abrams, “Eradicating pet and urine odors may be just as traumatizing and the only option, if the odor does appear to be eradicated significantly, is time, patience and understanding.”

Robert Kravitz is a frequent writer for the professional cleaning, carpet cleaning and building industries. He can be reached at [email protected].